1. Field of the Invention
The present invention relates to a reading device of polarimetric and interferometric sensors.
2. Discussion of the Background
To decode data coming from a network of coherence multiplexed sensors, it is necessary to compensate the phase shifts with an interferometric reading device. Depending on the structure of the sensor network, optical fiber Mach-Zehnder type interferometers or Michelson type interferometers are used. In the particular case of low coherence multiplexing, it is difficult to use nonbirefringent optical fibers considering the precision required for the adjustment of the length of the fiber sections used in the Mach-Zehnder type passive interferometers. In the general case, the Michelson interferometer is widely used in the laboratory considering its great versatility and its ease of use. However, it is difficult to use the Michelson interferometer outside the laboratory, for example, at an industrial site, because of the fragility of the mobile mirrors of this interferometer.
The device of FIG. 1 consists of a light source 1 supplying a coherence multiplexed sensor network 2. This network is a polarimetric type multipoint monofiber network, which includes fiber F and n sensors (MO, Ml, . . . , Mn) positioned between polarization coupling points made on fiber F.
Network 2 is followed by a diverting fiber 3 which ends in a polarizer 4. Following polarizer 4, a reading device 5 which is, in the example shown, a Michelson type interferometer, is connected.
The n sensors of network 2 are coherence multiplexed. Interferometric reading device 5 is used to compensate for the delays or phase shifts due to the various sensors. This device exhibits the drawbacks cited above.